In modern motor vehicles, it is more and more common to use devices for a level adjustment, by which the chassis can be lifted or lowered in relation to the chassis suspension. Such a device includes a damping device with a piston-cylinder unit, that is arranged between the wheel-carrier and the chassis, where it is decoupled via a strut bearing. The piston-cylinder unit comprises a spring, whose base point is e.g. adjustable by using a ball screw drive, in order to regulate the level. For this purpose, the spring is supported on a disc, which is coupled by using a nut of the ball screw drive. The nut can be actively turned by using a drive mechanism, so that it can move along the stationarily fixed spindle of the ball screw drive in axial direction. The disc is also moved by using this axial motion of the nut, and along with it the spring. The described arrangement can be varied in such a way that the spindle of the screw drive is actuated.
For the installation of the ball screw drive, which may comprise a corresponding drive mechanism, or to which such a mechanism is aligned, it is thus far customary, to push a spacing sleeve onto the piston-cylinder unit, or the suspension strut, wherein the spacing sleeve rests with its lower end on the wheel-carrier and on which the ball screw drive is supported on its upper end. An adapter sleeve is furthermore pushed onto the cylinder of the piston-cylinder unit, since the outer diameter of the cylinder features great tolerances and due to which it is not possible that the ball screw drive or its hollow cylindrical spindle can be directly placed or mounted onto the cylinder.
Thus, such a level adjustment device has an elaborate design when it comes to the needed components and its installation is complicated. Furthermore, there is the problem that the level adjustment device is acoustically coupled to the chassis suspension via the spacing sleeve and the adapter sleeve, which can have negative effects in view of a possible noise generation.
A device for a level adjustment in accordance with the characteristics of the preamble of claim 1 has become known from the DE 10 2009 057 003 A1. The damping pipe 52 of the cylinder is mounted in this case with its pin-like extension 56a on the strut side via a damping bearing 22. The damping pipe 56 can freely swing with the damping bearing 22 and is fully decoupled from any components with regards to vibrations that are supported via the suspension strut bearing 20 on the motor vehicle suspension side.